This invention relates in general to power on reset circuits for use in initializing microprocessor-based systems.
When operating microprocessor-based systems, it is necessary to provide a logic reset signal to initialize the microprocessor when power is first applied. Various reset circuits for providing this initializing reset signal are known. However, known power on reset circuits consume considerable power when operating which is a disadvantage.
In addition, it is advantageous to provide a reliable reset pulse to re-initialize the microprocessor whenever a power line transient or momentary power outage occurs. Known power-on reset circuits for providing such protection are highly complex and/or are available only in the form of an integrated circuit, such as that shown in U.S. Pat. No. 4,013,902--Payne (Mar. 22, 1977). Simple independently adjustable circuitry for providing both initialization at first power "on" and re-initialization reset signals in response to low voltage power transients are believed to be unavailable.